The top output shows, among other things, load average, CPU usage percentages and I/O wait (iowait) percentage. The iowait percentage is the percentage of time the CPU is waiting for an I/O to complete. The output below shows a fairly high load average over the past 1 minute (10.40) for the number of CPUs. It also shows that the CPUs are mostly in use (idle=3.0%) and that I/O wait percentage is low (0.4%).

Determining that there is high load is one thing. Finding the source of the load is another (whether it be CPU or I/O). Use the output from top to help determine if the high load is due to CPU or I/O. If the high load is due to CPU, see the Action section of theTroubleshooting CPU document for actions that can help alleviate CPU issues. If the high load is due to I/O wait percentage, then it might be related to disk I/O. See the Apache Geode Documentation for actions that can help alleviate disk issues for persistent regions.